1. Field of the Invention
The present invention relates to an apparatus for chemical mechanical polishing (CMP), and more particularly, to a slurry supply system having an homogenizer for distributing homogenized slurry.
2. Description of the Related Art
Unevenness of wafer surface is a serious problem, due to the high-integration and multiple layer structure of circuit supplying semiconductor devices. Therefore, in order to planarize or flatten uneven wafer surface, chemical-mechanical polishing (CMP) techniques are commonly used.
Removal rates and uniformity are important criteria for effective CMP technology. Variables such as processing conditions of the CMP equipment, the types of slurry and carriers, and others, greatly affect both removal rate and uniformity. The pH of the slurry and its ion concentration also have an impact on the planarization process.
In general, lumps of slurry sometimes occur when slurry is stored in a tank, greatly affecting the quality of the slurry, thereby causing scratches on wafers and decreasing manufacturing yield.
Conventionally, slurry is homogenized by a stirring and circulation apparatus; however, it is difficult and ineffective to homogenize the slurry with this conventional method.
An object of the present invention is to provide a slurry homogenizer.
Another object of the present invention is to provide a slurry supply system using the slurry homogenizer, which prevents the lumped slurry from entering the CMP equipment as much as possible.
In order to achieve these objects, the present invention provides a slurry homogenizer. A frame having an outlet is disposed on a driving means having a rotating shaft. A waterproof plate having a first opening is disposed in the frame and on the driving means. Part of the rotating shaft penetrates the first opening. A filter is disposed in the frame and on the waterproof plate. A first grinding pad has a second opening and is fitted on the rotating shaft through the second opening. The first grinding pad is disposed in the frame and above the waterproof plate. A knob is fitted on the top of the rotating shaft. The knob fixes the first grinding pad on the rotating shaft. A cover having a pipe is disposed on the frame. A second grinding pad having a third opening is fitted on the pipe and disposed in the frame. The second grinding pad and the first grinding pad are separated by a fixed distance.
The present invention improves on the prior art in that the slurry supply system uses the slurry homogenizer. Thus, the present invention can thoroughly break and mill the slurry lumps, thereby homogenizing the slurry, improving uniformity and manufacturing yield.